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CUET · MATHS · PYQ PAPER 2023

Which of the following functions is onto?

  1. A \(f: R \rightarrow R , f(x)=x^2\)
  2. B \(f: R \rightarrow R , f(x)=x^2+1\)
  3. C \(f: R \rightarrow R , f(x)=x^2-1\)
  4. D \(f: R \rightarrow R , f(x)=2 x+1\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(f: R \rightarrow R , f(x)=2 x+1\)

Step-by-step Solution

Detailed explanation

Consider \(f(x) = 2x+1\). Let \(y \in R\) (codomain). \(y = 2x+1 \implies x = \frac{y-1}{2}\) For every \(y \in R\), \(x = \frac{y-1}{2}\) is a real number. Range \(= R\). Since Range \(= \text{Codomain}\), \(f: R \rightarrow R , f(x)=2 x+1\) is onto.
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